1. Field of the Invention
The present invention relates to a method and apparatus for arranging light-emitting diodes (LEDs) or light-emitting elements to be supplied so that characteristics of adjacent LEDs or light-emitting elements in a display or the like are made substantially equal.
Incidentally, in this specification, an LED chip per se is referred to as “light-emitting element” and an integrated device including an optical device such as a package resin or a lens system mounted with the LED chip is referred to as “light-emitting diode” or “LED”.
2. Description of Related Art
After characteristics of produced LEDs are once inspected, the LEDs are arranged in inspecting order or at random and supplied to a customer. For example, taping as shown in FIG. 4 is used as a supply method. In this method, results of characteristic inspection are ranked into some grades by a certain characteristic (e.g., light intensity). LEDs 11 of the same rank are put on a corrugated board tape 14 through leads 12 extended from light-emitting portions 13. The leads 12 are stuck onto the corrugated board tape 14 by a pressure-sensitive adhesive tape 15 from above so that the LEDs 11 are fixed. The term “ranking” means classification of the light-emitting elements/LEDs by a certain width with respect to a certain characteristic value.
The method is also applied to the stage of light-emitting elements. That is, light-emitting elements 18 of the same rank as a result of characteristic inspection of the light-emitting elements are put on a palette 16 having a plurality of concave portions 17 arranged as shown in FIG. 5.
Each of the ranks is however considerably wide. Accordingly, when a plurality of LEDs of the same rank in light intensity are arranged in use, there maybe a disadvantage that light intensity varies because an LED high in light intensity in the rank and an LED low in light intensity in the rank are arranged so as to be adjacent to each other. In such a case, a resistor must be applied to the LED high in light intensity to balance light intensity as a whole. This is very trouble some. The same thing occurs in values of characteristics such as forward voltage and wavelength of emitted light. Even in the case where LEDs or light-emitting elements of the same rank are arranged in use, there is a problem that uneven appearance is caused by variation in light emission because characteristics of adjacent LEDs/light-emitting elements vary.
Therefore, an object of the invention is to provide a method and apparatus for arranging LEDs and light-emitting elements to make characteristics of adjacent LEDs/light-emitting elements substantially equal without variation. Incidentally, the invention may be applied to arrangement of light-emitting elements/LEDs produced but unsorted and may be applied to arrangement of light-emitting elements/LEDs ranked in advance.
The invention provides a method of arranging LEDs, including the steps of: performing characteristic measurement on LEDs to thereby obtain required characteristic values of the LEDs and storing the measured characteristic values in accordance with the LEDs; temporarily keeping the LEDs after storing the characteristic values; and rearranging a required number of LEDs to make the required characteristic values of adjacent LEDs substantially equal at a point of time when the required number of LEDs are collected.
In this method, all characteristic values of LEDs are stored in accordance with the LEDs after the values of one of characteristics (such as light intensity, forward voltage, and wavelength of emitted light) of the LEDs, which values being required to be made uniform, are measured. Then, the LEDs are temporarily kept and rearranged so that the characteristic values of adjacent LEDs are made substantially equal at a point of time when a required number of LEDs are collected.
Accordingly, when the LEDs supplied to a customer or to the next process are used in the arranging order, adjacent LEDs can emit light in a uniform manner without variation because the LEDs are arranged to make the characteristic values of adjacent LEDs substantially equal.
In this manner, because the characteristics of adjacent LEDs are made substantially equal, there can be provided a method for arranging LEDs without variation in characteristic.
In the method of arranging LEDs according to the invention, preferably, adjacent LEDs are arranged so that the characteristic value of one LED is not larger than that of the other LED.
Accordingly, the LEDs are arranged from the smallest characteristic value to the largest characteristic value, so that the difference between characteristic values of adjacent LEDs is minimized as a whole. In this manner, because the characteristics of adjacent LEDs are made substantially equal, there can be provided a method for arranging LEDs without variation in characteristic.
The invention also provides a method of arranging light-emitting elements, including the steps of: performing characteristic measurement on light-emitting elements to thereby obtain required characteristic values of the light-emitting elements and storing the measured characteristic values in accordance with the light-emitting elements; temporarily keeping the light-emitting elements after storing the characteristic values; and rearranging a required number of light-emitting elements to make the required characteristic values of adjacent light-emitting elements substantially equal at a point of time when the required number of light-emitting elements are collected.
In this method, all characteristic values of light-emitting elements are stored in accordance with the light-emitting elements after the values of one of characteristics (such as light intensity, forward voltage, and wavelength of emitted light) of the light-emitting elements, which values being required to be made uniform, are measured. Then, the light-emitting elements are temporarily kept and rearranged so that the characteristic values of adjacent light-emitting elements are made substantially equal at a point of time when a required number of light-emitting elements are collected.
Accordingly, when the light-emitting elements supplied to a customer or to the next process are used in the arranging order, adjacent light-emitting elements can emit light in a uniform manner without variation because the light-emitting elements are arranged to make the characteristic values of adjacent light-emitting elements substantially equal.
In this manner, because the characteristics of adjacent light-emitting elements are made substantially equal, there can be provided a method for arranging light-emitting elements without variation in characteristic.
In the method of arranging light-emitting elements according to the invention, preferably, adjacent light-emitting elements are arranged so that the characteristic value of one light-emitting element is not larger than that of the other light-emitting element.
Accordingly, the light-emitting elements are arranged from the smallest characteristic value to the largest characteristic value, so that the difference between characteristic values of adjacent light-emitting elements is minimized as a whole. In this manner, because the characteristics of adjacent light-emitting elements are made substantially equal, there can be provided a method for arranging light-emitting elements without variation in characteristic.
The invention further provides an apparatus of arranging LEDs, including: a characteristic value measuring unit for performing characteristic measurement on LEDs to thereby obtain required characteristic values of the LEDs; a temporarily keeping unit for temporarily keeping the LEDs subjected to the characteristic measurement while giving numbers to the LEDs in measuring order; a characteristic value storage unit for storing the characteristic values of the LEDs in association with the numbers of the LEDs; an arrangement sequence calculation unit for remaking an arrangement sequence of the LEDs by computer so that the difference between the characteristic values of adjacent ones of the LEDs is minimized throughout all the LEDs; and a moving arrangement unit for moving the LEDs from the temporarily keeping unit to a regular supply unit and arranging the LEDs in accordance with the arrangement sequence remade by the arrangement sequence calculation unit.
In this manner, in the apparatus for arranging LEDs according to the invention, values of one of characteristics (such as light intensity, forward voltage, and wavelength of emitted light) of the LEDs, which values being required to be made uniform, are measured by the characteristic value measuring unit and the LEDs are kept by the temporarily keeping unit while temporary numbers are given to the LEDs respectively. Because the characteristic values of the LEDs are stored by the characteristic value storage unit in association with the temporary numbers, an arrangement sequence of the LEDs is remade by the arrangement sequence calculation unit so that the difference between the characteristic values of adjacent LEDs is minimized as a whole. The LEDs are moved from the temporarily keeping unit to a regular supply unit (taping, palette, sheet, etc.) and arranged in accordance with the arrangement sequence by the moving arrangement unit.
Accordingly, when the LEDs supplied to a customer or to the next process are used in the arranging order in the supply unit, adjacent LEDs can emit light in a uniform manner without variation because the LEDs are arranged to make the characteristic values of adjacent LEDs substantially equal.
In this manner, because the characteristics of adjacent LEDs are made substantially equal, there can be provided an apparatus for arranging LEDs without variation in characteristic.
In the apparatus of arranging LEDs according to the invention, preferably, adjacent LEDs are arranged so that the characteristic value of one LED is not larger than that of the other LED.
Accordingly, the LEDs are arranged from the smallest characteristic value to the largest characteristic value, so that the difference between characteristic values of adjacent LEDs is minimized as a whole. In this manner, because the characteristics of adjacent LEDs are made substantially equal, there can be provided an apparatus for arranging LEDs without variation in characteristic.
The invention further provides an apparatus of arranging light-emitting elements, including: a characteristic value measuring unit for performing characteristic measurement on light-emitting elements to thereby obtain required characteristic values of the light-emitting elements; a temporarily keeping unit for temporarily keeping the light-emitting elements subjected to the characteristic measurement while giving numbers to the light-emitting elements in measuring order; a characteristic value storage unit for storing the characteristic values of the light-emitting elements in association with the numbers of the light-emitting elements; an arrangement sequence calculation unit for remaking an arrangement sequence of the light-emitting elements by computer so that the difference between the characteristic values of adjacent ones of the light-emitting elements is minimized throughout all the light-emitting elements; and a moving arrangement unit for moving the light-emitting elements from the temporarily keeping unit to a regular supply unit and arranging the light-emitting elements in accordance with the arrangement sequence remade by the arrangement sequence calculation unit.
In this manner, in the apparatus for arranging light-emitting elements according to the invention, values of one of characteristics (such as light intensity, forward voltage, and wavelength of emitted light) of the light-emitting elements, which values being required to be made uniform, are measured by the characteristic value measuring unit and the light-emitting elements are kept by the temporarily keeping unit while temporary numbers are given to the light-emitting elements respectively. Because the characteristic values of the light-emitting elements are stored by the characteristic value storage unit in association with the temporary numbers, an arrangement sequence of the light-emitting elements is remade by the arrangement sequence calculation unit so that the difference between the characteristic values of adjacent light-emitting elements is minimized as a whole. The light-emitting elements are moved from the temporarily keeping unit to a regular supply unit (taping, palette, sheet, etc.) and arranged in accordance with the arrangement sequence by the moving arrangement unit.
Accordingly, when the light-emitting elements supplied to a customer or to the next process are used in the arranging order in the supply unit, adjacent light-emitting elements can emit light in a uniform manner without variation because the light-emitting elements are arranged to make the characteristic values of adjacent light-emitting elements substantially equal.
In this manner, because the characteristics of adjacent light-emitting elements are made substantially equal, there can be provided an apparatus for arranging light-emitting elements without variation in characteristic.
In the apparatus of arranging light-emitting elements according to the invention, preferably, adjacent light-emitting elements are arranged so that the characteristic value of one light-emitting element is not larger than that of the other light-emitting element.
Accordingly, the light-emitting elements are arranged from the smallest characteristic value to the largest characteristic value, so that the difference between characteristic values of adjacent light-emitting elements is minimized as a whole. In this manner, because the characteristics of adjacent light-emitting elements are made substantially equal, there can be provided an apparatus for arranging light-emitting elements without variation in characteristic.